The present invention relates generally to a thermoplastic web of film. More specifically, the present invention relates to a web of film utilized to make flexible containers.
Thermoplastic webs of film can be utilized to create flexible containers for housing products. These flexible containers are utilized, among other areas, in the medical industry for containing, inter alia, parenteral solutions such as intravenous solutions, dialysis solutions, frozen drugs, nutrition products, respiratory therapy products, and plasma. When these containers are utilized in the medical industry, because they will contain fluids or solids that are introduced into a patient's body, it is necessary for the containers to be: essentially transparent; flexible; essentially free of extractables; and capable of maintaining the product contained therein under sterile conditions until the product is accessed or removed from the flexible container.
Therefore, the film from which these containers are constructed must also meet these requirements. It is also important that the film, used in constructing these containers, is sufficiently strong so that the containers constructed from the film have sufficient strength. Furthermore, for economic reasons, it is desirable that any such film be readily constructed into a flexible container on commercially available, or easily adapted, production machinery.
In constructing flexible containers, one method of making a flexible container from a web of film is to seal the web of film, either onto itself, or onto a corresponding web of film, to create the sides of the container for housing the product. One method for sealing such containers is RF (radio frequency) sealing. RF sealing utilizes radio frequency energy to excite the molecules of the film thereby heating the film and causing it to melt and seal to a corresponding surface of a web of film. In this regard, certain plastic materials are RF energy responsive in that, when exposed to radio frequency energy, the molecules of the material or film are excited and thereby heated. As used in this patent application, "RF responsive" or "RF energy responsive" means that the material will be heated to its softening temperature or melting point when exposed only to RF energy between 25 and 30 MHz.
Heretofore some flexible containers have been constructed from polyvinyl chloride. In order to make polyvinyl chloride sufficiently flexible, so that it can be used to create flexible containers, plasticizers have been added thereto. The toxicity of plasticizers has increasingly become a matter of concern both in processing the material into a web of film and in the end use of the film. In the medical industry, typically, diethylheyylphthalate (DEHP) or epoxidized and oils are utilized as plasticizers for polyvinyl chloride. Recently, however, DEHP has become a suspect compound in that there is continued testing to determine if DEHP is a health hazard.
Because the flexible containers, in the medical industry, are utilized to house fluids that are introduced into a patient's body, these containers must be sterilized after they are created. In this regard, it is known to autoclave the containers at temperatures of up to approximately 270.degree. F.
Although there are some materials that would be desirable for constructing flexible containers for use in the medical industry, they have not heretofore been utilized. One of the problems with some of these materials is that, due to their softening temperature, they cannot be utilized to create flexible containers that must be autoclaved. Furthermore, some materials cannot be run on standard or easily modified production machinery to create flexible containers. Moreover, some materials do not seal well to themselves and accordingly, do not create containers having strong seals.
There is therefore a need for a web of film for creating a flexible container that can be used on conventional machinery, such as machinery that utilizes RF energy to create side seals, and that does not contain a DEHP plasticizer.